Many formulations such as inks, paints and millbases require effective dispersants for uniformly distributing a particulate solid in an aqueous or polar organic medium. For inks, it is desirable for ink manufacturers to generate printed products of high resolution and quality. The adaptability of a printing process to cater for the ever widening range of base substrates, resins and pigments is a challenge. The pigment dispersion should be compatible with the different formulations used to ensure good adhesion and resistance of the final coating. Poor pigment dispersion or stabilisation can result in agglomeration or settling within the polar organic liquid medium or an aqueous liquid medium (e.g., ink or coating) lowering the gloss and aesthetic appeal.
U.S. Pat. No. 7,265,197 discloses dispersing pigments in ink compositions with a dispersant having formula:
where R1 is individually selected from the group consisting of H and CH3, and n is an integer from 4 to 400.
International publication WO 2008/028954 discloses imide dispersant compounds containing terminal acidic groups in both a polar and a non-polar organic medium, where the dispersant compound is represented by the structure
where T is —(CH2)3— or —CH2CH(CH3)—; R′ is H or C1-50-optionally substituted hydrocarbyl group, or C1-50-optionally substituted hydrocarbonyl; Y is C2-4-alkyleneoxy; x is 2 to 90; and q is 1 or 2, with the proviso that in Formula (1a), when q is 1, T is —(CH2)3—, and when q is 2, T is —(CH2)3— or —CH2CH(CH3)—
U.S. Pat. No. 5,688,312 discloses an ink composition comprised of a colorant and an imide or bisimide with a viscosity of from about 1 centipoise to 10 centipoise at a temperature of from about 125 to 180° C. The imide or bisimide may be prepared by reacting phthalic anhydride and a mono- or di-amine. The monoamine may be, for example, dodecylamine, or stearylamine. The diamine may be 1,12-dodecanediamine.
International Patent Application WO 2007/139980 discloses a reaction product of at least one di-anhydride with at least two reactants which are different from each other, each of which reactants contains a primary or secondary amino, hydroxyl or thiol functional group, and at least one of which reactants is polymeric. The reaction product is useful in compositions such as inks and coatings.
U.S. Pat. No. 6,440,207 discloses a process for preparing dispersible dry organic pigments for aqueous systems by (a) milling a mixture containing (1) one or more organic pigments, (2) at least about 1% by weight, relative to the organic pigment, of one or more aromatic polyalkylene oxide dispersants, (3) 0 to about 10 parts by weight, relative to the organic pigment, of a milling liquid in which the organic pigment is substantially insoluble, (4) 0 to about 50% by weight, relative to the organic pigment, of one or more milling additives other than dispersant (2), and (5) 0 to about 20% by weight, relative to the organic pigment, of one or more surface treatment additives; (b) optionally, adding to the milled pigment (6) one or more liquids in which the organic pigment is substantially insoluble in amounts such that the total solids content is not reduced below about 10%, and (7) one or more multivalent metal salts and/or one or more quaternary ammonium salt; and (c) isolating the milled organic pigment. The aromatic polyalkylene oxide dispersant may be prepared by reacting in an autoclave containing 250 g of deionized water 19.8 g (0.100 mol) of 1,8-naphthalic anhydride and 105 g (0.105 mol) of Jeffamine™ XTJ-506 (83 wt % ethylene oxide, 17 wt % propylene oxide). The autoclave was sealed, heated with stirring to 150° C., and maintained at 150° C. for five hours. After the reaction had cooled, the resultant brown liquid was discharged into a beaker to which was then added 15 g of decolorizing charcoal. After stirring overnight, the suspension was filtered and the filter cake washed with water, yielding approximately 500 g of an amber-colored filtrate having 23.63% solids content. The dry pigment can be employed in water-based paint systems.